Color photographic light-sensitive materials of the type developable with a color developing agent, such as paraphenylenediamine, are well known and include silver halide photographic materials containing a color-forming coupler. Techniques for improving white background and adjusting gradation are important factors which affect the image quality. In particular, conventional methods use various hydroquinones to improve white background (i.e., inhibit color fog) in color photographic materials.
For example, methods using straight chain monoalkylhydroquinones are described in U.S. Pat. Nos. 2,728,659 and 3,917,485. Methods using branched monoalkylhydroquinones are described in U.S. Pat. No. 3,700,453, West German Patent Laid-Open No. 2,149,789, and JP-A-No. 50-156438 and JP-A-No. 49-106329 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application"). Methods using straight chain dialkylhydroquinones are described in U.S. Pat. Nos. 2,728,659 and 2,732,300, British Patent Nos. 752,146 and 1,086,208, and Chemical Abstracts, Vol. 58, 6367h. Methods using branched dialkylhydroquinones are described in U.S. Pat. Nos. 3,700,453, 2,732,300 and 4,121,939, British Patent No. 1,086,208, Chemical Abstracts, Vol. 58, 6367h, JP-A-No. 50-156438 and JP-B-No. 50-21249 (the term "JP-B" as used herein refers to an "examined Japanese patent publication").
Furthermore, methods using alkylhydroquinones as color stain inhibitors are described in British Patent Nos. 558,258, 557,750 (U.S. Pat. No. 2,360,290), 557,802 and 731,301 (U.S. Pat. No. 2,701,197), U.S. Pat. Nos. 2,336,327, 2,403,721, 2,735,765, and 3,582,333, West German Patent Laid-Open No. 2,505,016 (JP-A-No. 50-110337), and JP-B-No. 56-40816 and JP-B-No. 56-21145.
Various methods have been proposed to inhibit color fog in the color developing solution.
Fog developed in a color developing bath is said to be roughly divided into three types. The first type is attributable to fog in a silver halide emulsion. The second type of fog is developed during the storage of a light-sensitive material between coating and development. The third type is attributable to couplers. In other words, this type of fog results from an indiscriminate reaction with an oxidation product of a developing agent present in a slight amount in a developing solution. It has been known that these types of fog can be prevented by the use of compounds containing a mercapto group, tetraazaindenes or the like. These compounds are disclosed in U.S. Pat. Nos. 3,954,474, 3,982,947, and 4,021,248, JP-B-No. 52-28660, and Research Disclosure, No. 17643. However, these compounds containing a mercapto group and tetraazaindenes can eliminate fog to some degree but are not sufficiently effective for the inhibition of color fog.
In recent years, as the demand for improvement in white background and adjustment of gradation has increased, various approaches have been proposed. For example, methods using compounds having a rather small molecular weight among the above-described hydroquinones are disclosed in JP-A-No. 62-239153, JP-A-No. 63-63033 and JP-A-No. 63-80250. However, further improvement in this field is still required.